1. Field of the Invention
The present invention relates to a cartridge having a chamber to hold a recording material used for printing therein. More specifically the invention pertains to a technique of transmitting information between a cartridge with a built-in sensor and the cartridge with such a chamber.
2. Description of the Related Art
Various printers and printing apparatuses are widely used for printing; for example, printing apparatuses that eject inks onto printing paper for recording, such as ink jet printers, and printing apparatuses that use toners for printing. A cartridge set on such a printing apparatus has a chamber to hold a recording material like an ink or a toner therein. Management of the remaining quantity of the recording material is an important technique in the printing apparatus. While the printing apparatus counts and manages the consumed quantity by software, a proposed technique uses a sensor mounted on the cartridge for direct measurement (see, for example, Patent Laid-Open Gazette No. 2001-147146).
A variety of sensors may be applicable for the sensor mounted on the cartridge. When the recording material to be detected is a conductive ink, the sensor may measure an electric resistance to determine the remaining quantity of ink. The sensor may use a piezoelectric element located in a resonance chamber disposed in the chamber of holding the recording material to measure the resonance frequency of the piezoelectric element and thereby detect the presence or the absence of the recording material in the resonance chamber. The sensor may measure a temperature, a viscosity, a humidity, a particle size, a hue, a remaining quantity, or a pressure of the recording material, such as ink. In such measurements, a special sensor may be used according to the physical property to be measured. For example, when the physical property to be measured is the temperature, the sensor may be a thermistor or a thermocouple. When the physical property to be measured is the pressure, the sensor may be a pressure sensor.
In the prior art cartridge with such a sensor, the detection is carried out under a fixed detection condition and may not have a sufficiently high reliability. For example, when the sensor mounted on the cartridge detects the presence or the absence of the recording material held in the chamber, a variation in composition of the recording material may change the optimum detection condition. The prior art cartridge cannot sufficiently assure the reliability of the detection, unless the circuit structure for the detection is adjusted for the new optimum detection condition. Such adjustment of the circuit structure, however, takes much time and labor and undesirably increases the cost.
Another problem may arise in the prior art cartridge, when the detection result gives a binary signal, for example, representing the presence or the absence of ink. When the detection circuit breaks down to continuously output an identical value of the binary signal, the malfunction cannot be detected accurately. This causes the poor reliability of the detection result.